A Case-Based Comparison of the American Thyroid Association and Thyroid Imaging Reporting & Data System Guidelines

Thyroid nodules are a common clinical finding. Approximately 4-7% of the population have a palpable nodule on physical exam,1 while up to 70% of the population have a nodule detected incidentally on ultrasound.2 The vast majority of nodules are benign, however, approximately 5-13% of thyroid nodules detected on imaging are at risk of malignancy.3 Some malignant nodules, especially those smaller than 1 cm, can exhibit indolent behavior and do not require aggressive treatment.4 Therefore, thyroid nodules need to be accurately assessed to avoid overdiagnosis and overtreatment of nodules which would not otherwise affect patient morbidity. The American Thyroid Association (ATA) addressed this challenge by developing a set of ultrasound pattern-based guidelines for thyroid nodule management in 2009, which were updated in 2015.5 Other societies have since published similar guidelines, such as the Thyroid Imaging Reporting & Data System (TI-RADS) by the American College of Radiology in 2017. TI-RADS was similarly intended to risk-stratify nodules based on ultrasound appearance, but uses a points-based approach. The purpose of this review is to provide an overview of thyroid nodule evaluation and management through a case-based comparison using the ATA and TI-RADS guidelines.